Drop on demand ink jet technology is widely used in the printing industry. Printers using drop on demand ink jet technology typically use either thermal ink jet technology or piezoelectric technology. Even though they are more expensive to manufacture than thermal ink jets, piezoelectric ink jets are generally favored, for example because they can use a wider variety of inks.
Piezoelectric ink jet print heads include an array of piezoelectric elements (i.e., transducers or PZTs). One process to form the array can include detachably bonding a blanket piezoelectric layer to a transfer carrier with an adhesive, then dicing the blanket piezoelectric layer to form a plurality of individual piezoelectric elements. A plurality of dicing saw passes can be used to remove all the piezoelectric material between adjacent piezoelectric elements to provide the correct spacing between each piezoelectric element.
Piezoelectric ink jet print heads can typically further include a flexible diaphragm to which the array of piezoelectric elements is attached. When a voltage is applied to a piezoelectric element, typically through electrical connection with an electrode electrically coupled to a power source, the piezoelectric element bends or deflects, causing the diaphragm to flex which expels a quantity of ink from a chamber through a nozzle (i.e., aperture or orifice) in an aperture plate (i.e., nozzle plate). The flexing further draws ink into the chamber from a main ink reservoir through an opening to replace the expelled ink.
Piezoelectric elements can be manufactured from a bulk material that includes lead. To reduce the impact of lead-based piezoelectric actuators on the environment, other ink ejection technologies have been researched. For example, electrostatic actuators include the use of an electrode that, when powered through a supplied voltage, attracts and flexes a silicon membrane (e.g., a diaphragm) to draw ink from an ink supply into an ink chamber formed in part by the membrane. When the voltage is removed from the electrode, the silicon membrane relaxes, thereby increasing pressure in the ink chamber and ejecting ink from a nozzle in an aperture plate.
As printing technologies improve, the physical size of the actuators decreases, with a corresponding increase of in the number of nozzles and actuators within a given area of the printhead. Forming actuator membranes for electrostatically actuated ink jet printheads becomes increasingly difficult with decreasing sizes. For example, with current technology, a rectangular actuator membrane for an electrostatically actuated printhead may have an area of about 4 mm by 12 mm. These small actuators are difficult to form and are prone to cracking.
A simplified method for forming an array of electrostatic actuators that increases manufacturing throughput would be desirable.